High power LED lamp with heat dissipation enhancement

ABSTRACT

A high power LED lamp comprises a container having a cavity to fill with a liquid, a light source module for providing a high power LED source light to penetrate through the liquid, and an axial thermal conductor having a first portion nearby the light source module and a second portion extending in the liquid along an axial direction of the cavity to far away from the light source module to evenly transfer heat from the light source module through the liquid to the container.

This application is a division of application Ser. No. 11/487,386, filedon Jul. 17, 2006, the entire contents of which are incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention is related generally to a lamp and, moreparticularly, to a high power light-emitting diode (LED) lamp forillumination purpose.

BACKGROUND OF THE INVENTION

Due to its long lifetime, power saving and environment protection, LEDhas been widely used in decorative lamps such as underwater lights andindicative lamps such as traffic lights. However, it is still notsuitable for illumination purpose since the brightness per unit powerconsumption it generates is not high enough, the heat dissipation it isprovided with is not efficient enough, and the emission angle of lightsit radiates is not wide enough. Along with the improvement of white LED,the brightness per unit power consumption is gradually enhanced.Recently, for example, it is commercialized of white LED brighter thantraditional incandescent bulb, which is up to 30 lm/W, and it is alsoexpected in a few days the commercialization of white LED brighter thanfluorescent tube, which is about 100 lm/W. Therefore, the heatdissipation and the lighting angle are the problems to be solved forusing LED in luminaries.

FIG. 1 shows a typical low power LED 100, which comprises alens-effective epoxy resin 110 covering over a semiconductor die 102,and a pair of anode pin 106 and cathode pin 108 electrically connectedto the semiconductor die 102 through electrodes and a gold wire 104. Theheat produced by the low power LED 100 is so tiny that it could be welldissipated by conducting through the pair of anode pin 106 and cathodepin 108 to the copper foil of the printed circuit board (not shown inFIG. 1) that the low power LED 100 is mounted for further dissipating tothe air of the environment. This type of low power LED 100 has the powerconsumption less than 0.3-0.4 W and is applied for decorative lamps andindicative lamps. FIG. 2 shows a conventional low power LED lamp 112,which comprises a standard bulb base 120 bounded with a shell 122, aprinted circuit board 116 fixed within the shell 122, several low powerLED packages 100 welded on the printed circuit board 116, a layer ofresin 114 filling in the shell 122 to protect the printed circuit board116 and the pins of the low power LED packages 100, and a powerconversion and driving module 118 connected between the printed circuitboard 116 and the base 120 for driving the low power LED packages 100.In the low power LED lamp 112, the heat produced by the low power LEDpackages 100 is conducted to the copper foil of the printed circuitboard 116 and then dissipated therefrom, and no heat sink is provided.The shell 122 is made of either metal or plastic. However, the use ofmetal for the shell 122 is for mechanical strength but not for thermalconduction or heat dissipation.

FIG. 3 shows a conventional high power LED 124, in which a pair of anodepin 138 and cathode pin 140 are electrically connected to asemiconductor die 130 through electrodes and gold wires 132 and 133, alayer of resin 128 fixes the semiconductor die 130 on a heat sink 136, aplastic shell 134 contains the core structure, and an optical lens 126is positioned on the resin 128 and bounded to the plastic shell 134.This type of high power LED 124 consumes more than 0.3 W, and because ofthe great heat generation, requires heat dissipation means forpreventing the high power LED 124 from overheating. FIG. 4 shows a heatsink structure 142 for the high power LED 124, which comprises a metalcore printed circuit board 144 attached to the heat sink 136, and fins146 attached to the metal core printed circuit board 144 for heatdissipation. The heat produced by the high power LED 124 is conductedthrough the heat sink 136 and the metal core printed circuit board 144to the fins 146, where the natural air convection dissipates the heat tothe air of the environment. The heat sink 136 is made of good thermalconductor, such as metal, graphite, carbon fiber, ceramic and theircompound. FIG. 5 shows a conventional front dissipation high power LEDlamp 148, which comprises a reflective cup 150 made of highly thermallyconductive metal whose outside surface is formed with ring fins 158, anoptical lens 152 made of glass or plastic on the aperture of thereflective cup 150, a high power LED package 124 on the bottom of thereflective cup 150, and a power conversion and driving module 154connected between the high power LED package 124 and a standard bulbbase 156. The light emitted by the high power LED package 124 isreflected by the reflective cup 150 to pass through the optical lens152, and the heat produced by the high power LED 124 is conducted by thereflective cup 150 to the fins 158 to dissipate therefrom by natural airconvection. In this high power LED lamp 148, even though the fins 158increase the heat dissipation area for air convection, the thermalconduction path is too long to fast dissipate the heat from the highpower LED package 124 to the fins 158, resulting in the high power LEDpackage 124 overheated. To solve this overheat problem, it is proposed aback dissipation structure as shown in FIG. 6, in which a backdissipation high power LED lamp 160 comprises an optical lens 162 over ahigh power LED package 124, and a heat pipe 164 connected between thehigh power LED package 124 and a power conversion and driving module168. Fins 166 are formed on the heat pipe 164, and the power conversionand driving module 168 has a pair of power input terminals 170. The heatproduced by the high power LED package 124 is conducted to the heat pipe164 and dissipated by the fins 166 by natural air convection. Since thethermal conduction path is shorter, the heat pipe 164 is capable offaster dissipating the heat from the high power LED package 124 by thefins 166. However, an environment having excellent airflow is requiredfor such back dissipation lamp 160 for better heat dissipation from thefins 166 by natural air convection. When the back dissipation high powerLED lamp 160 is applied for illumination purpose, such as embedded andceiling fitting, the environment will not have excellent airflowcondition, and the heat dissipation is dramatically degradedaccordingly. FIG. 7 is a perspective diagram of the back dissipationhigh power LED lamp 160 applied for an embedded fitting, where the highpower LED lamp 160 is positioned within a lampshade 172 that is fixedbetween a floor plate 174 and a ceiling plate 176. Due to the high powerLED lamp 160 covered by the lampshade 172, the air convection is limitedby the lampshade 172, resulting in poor heat dissipation. FIG. 8 is aperspective diagram of the back dissipation high power LED lamp 160applied for a ceiling fitting, where the high power LED lamp 160 isfixed between a floor plate 174 and a ceiling plate 176, and thus thenatural air convection to enhance the heat dissipation is limited by theshallow space between the floor plate 174 and the ceiling plate 176.Once the number of the high power LED lamps 160 for a ceiling fitting islarger, the accumulated temperature increase will degrade the heatdissipation efficiency. Moreover, in the tropical zone or thesubtropical zone, the air temperature between the ceiling plate 176 andthe floor plate 174 is often higher than 40° C., which willsignificantly limit the heat dissipation for the high power LED lamp160.

Thermal delivery could be attained by conduction, convection andradiation. In the high power LED lamp 148 and 160, for heat dissipationenhancement, it is only used thermal conduction provided by thermallyconductive material and natural thermal convection caused by larger heatsurface in air environment at room temperature. With the same heatdissipation surface, the dissipated heat by natural air convection isonly ¼ to 1/10 time of that by forced air convection such as by a fan.In addition, to improve the dissipation efficiency, the heat sink fornatural air convection is required to have greater gaps between theadjacent fins thereof, resulting in larger volume in space. Withrespective to the forced air convection, however, it is not practical inconsideration of the lifetime and reliability of fan compared with thelong-term reliability of high power LED. Therefore, the increasing powerof LED for illumination purpose makes it more difficult to solve theheat dissipation problem.

Because the junction working temperature of high power LED is requiredlower than 120° C. to avoid overheating, and the brightness (in lumens)and the lifetime of high power LED both are inversely proportional tothe junction working temperature, the enhancement of heat dissipation toreduce the junction working temperature of high power LED becomes thefundamental of the application of high power LED for illuminationpurpose. FIG. 9 shows the relationship between the brightness and thejunction working temperature of high power LED, in which for an idealcase, the junction working temperature of high power LED is requiredlower than 95° C. for the brightness higher than 80%. FIG. 10 shows therelationship between the lifetime and the junction working temperatureof high power LED, in which for an ideal case, the junction workingtemperature of high power LED is required lower than 95° C. for thelifetime longer than 50 khr.

The high power LED lamp 148 has another drawback of optical loss due tothe multiple reflections of the light within the reflective cup 150 andthe reflection on the lens 152 when light passes therethrough, whichlowers the useful efficiency of the light emitted by the high power LEDlamp 148.

U.S. Pub. No. 2004/0004435 proposed a packaged LED, which comprises acap having a cavity to fill with a cooling liquid to package a LED chipsuch that the cooling liquid could provide heat dissipation by directcontacting the LED chip. In theoretic, it seems to be effective for heatdissipation enhancement; however, it will not be significantly effectivein practice since the cooling liquid behaves only as a thermal conductorin this structure. It is known that a liquid has poorer thermalconductivity than a solid, and thereby the replacement of theconventional resin with the cooling liquid to directly contact the LEDchip will degrade the heat dissipation. In further detail, the activejunction on the LED chip works at a temperature of around 110° C. forhigh power applications, which will heat the cooling liquid around theactive junction to a very high temperature and produce a temperaturegradient through the cooling liquid to the cap. Since the cooling liquidis a poor thermal conductor, it will not fast transfer the heat from theLED chip to the ambient air. As a result, the cooling liquid around theactive junction will become very hot, and the heat will be kept thereof.Another drawback is that the package is too small to contain a little ofcooling liquid, and therefore nothing beneficial to heat dissipation isprovided. Moreover, since the working temperature of the active junctionon the LED chip is around 110° C., the active junction surrounded by thecooling liquid may become a bubble generator to further degrade the heatdissipation. Since the heat cannot be dramatically removed from the paththrough the cooling liquid, the heat produced by the LED chip is stilldominantly transferred through the electrodes and wire to the pins as aconventional LED does. A further drawback may be introduced into thispackage. Since it is the bare chip contacted by the cooling liquid, thecooling liquid may damage the LED chip because of erosion.

Another issue is discussed in the following. FIG. 11 shows the spatialdistribution of light emitted by a traditional incandescent lamp, inwhich there is more than 60% of the brightness within the angle of 280degrees. FIG. 12 shows the spatial distribution of light emitted by atraditional high power LED, in which the angle for 60% of the brightnessis 110 degrees. Therefore, another problem to be solved for high powerLED applied for ambient lighting is wider and uniform illumination.Namely, there is a need of optical design to spread the effectivelighting angle of high power LED for illumination purpose.

Accordingly, it is desired a high power LED lamp with improved heatdissipation, wider lighting angle and higher brightness.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a high power LED lampfor illumination purpose.

Another object of the present invention is to provide a low cost highpower LED lamp.

A further object of the present invention is to improve the heatdissipation of a high power LED lamp.

Yet another object of the present invention is to provide a high powerLED lamp having wider lighting angle.

Still another object of the present invention is to improve thebrightness of a high power LED lamp.

In a high power LED lamp, according to the present invention, acontainer has a cavity filled with a liquid, a light source moduleprovides a high power LED source light to penetrate through the liquid,and an axial thermal conductor has a first portion nearby the lightsource module and a second portion extending in the liquid along anaxial direction of the cavity to far away from the light source module.When the light source module warms up, the axial thermal conductorevenly transfers heat from the light source module through the liquid tothe container. As a result, it is attained fast and great heatdissipation for the light source module.

The liquid enhances the heat dissipation, spreads the lighting angle andincreases the brightness. Preferable, thermal convection is caused inthe liquid for further enhancement of heat dissipation. It is a low costapproach, which costs only ⅕ to 1/10 time than the conventional metalfins. When the light emitted, by the light source module penetratesthrough the liquid, it is diffused to spread the lighting angle, and thetotal reflection between the liquid and the container may have lightfocusing effect and increase the brightness.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading thesubsequent detailed description and examples with references made to theaccompanying drawings; wherein:

FIG. 1 shows a conventional low power LED;

FIG. 2 shows a conventional low power LED lamp;

FIG. 3 shows a conventional high power LED;

FIG. 4 shows a conventional heat sink structure for a high power LED;

FIG. 5 shows a conventional front heat dissipation high power LED lamp;

FIG. 6 shows a conventional back heat dissipation high power LED lamp;

FIG. 7 is a perspective diagram of a conventional back heat dissipationhigh power LED lamp applied for embedded fitting;

FIG. 8 is a perspective diagram of a conventional back heat dissipationhigh power LED lamp applied for ceiling fitting;

FIG. 9 shows the relationship between the brightness and the junctionworking temperature of high power LED;

FIG. 10 shows the relationship between the lifetime and the junctionworking temperature of high power LED;

FIG. 11 shows the spatial distribution of light emitted by a traditionalincandescent lamp;

FIG. 12 shows the spatial distribution of light emitted by a traditionalhigh power LED;

FIG. 13 shows a high power LED lamp according to the present invention;

FIG. 14 shows the composition of the high power LED lamp of FIG. 13;

FIG. 15 shows a cross-sectional view of the sealing cap shown in FIG.14;

FIG. 16 shows a perspective diagram of floating dye particles for sidelighting of the high power LED lamp of FIG. 13;

FIG. 17 shows an embodiment of the present invention for ambientlighting;

FIG. 18 shows another embodiment of the present invention for ambientlighting;

FIG. 19 shows an embodiment of the present invention for ultra highpower ambient lighting;

FIG. 20 shows another embodiment of the present invention for ultra highpower ambient lighting;

FIG. 21 shows a further enhancement of heat dissipation according to thepresent invention; and

FIG. 22 shows a further embodiment of the present invention for ultrahigh power ambient lighting.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 13 shows a high power LED lamp 200 according to the presentinvention, and FIG. 14 is a decomposition diagram. In the high power LEDlamp 200, container 202 has a cavity 203 to fill with transparent ortranslucent liquid 204, light source module includes high power LEDpackage 206 consuming power of for example more than 0.3 W, mounted onmetal core printed circuit board 210 having power lines 222 therefrom,package resin 208 fixes the high power LED package 206 and the metalcore printed circuit board 210 on carrier 212 and provides water sealingfunction, axial fins assembly 211 is installed in front of the highpower LED package 206 and thermally connected to the carrier 212, axialthermally conductive tube 213 has one end inserted into positioning ring214 and water sealing cap 216 and the other end thermally connected tothe carrier 212 too, sealing material 218 on the sealing cap 216 sealsthe aperture of the container 202, and power conversion and drivingmodule 220 is connected between the light source module and standardbulb base 224, by which the electric power from power lines 226 isconverted to constant DC current through the power lines 222 to drivethe high power LED package 206. The cross-sectional view of the sealingcap 216 is shown in FIG. 15, which has wedged edge 232 and trench 234for the sealing material 218 to attain better sealing effect. Back toFIG. 13, the carrier 212, the axial thermally conductive tube 213 andthe axial fins assembly 211 are all made of good thermal conductor, andthe axial thermally conductive tube 213 and the axial fins assembly 211both extend along the axial direction of the cavity 203 and has an axiallength preferably between ¼ and one time of the axial length of cavity203. The axial thermally conductive tube 213 extends in the liquid 204at the back side of the carrier 212 and the axial fins assembly 211extends in the liquid 204 at the front side of the carrier 212 to faraway from the high power LED package 206 also, such that the heat may beconducted to the cooler portion of the liquid 204 by the axial thermallyconductive tube 213 and the axial fins assembly 211. The heat producedby the high power LED package 206 is conducted through the metal coreprinted circuit board 210 and the carrier 212 to the axial thermallyconductive tube 213 and the axial fins assembly 211, and is thentransferred to the liquid 204 as shown by the arrows in FIG. 13. Theliquid 204 further dissipates the heat by thermal conduction and thermalconvection to the container 202 to further dissipate to the ambient air.Since the container 202 provides huge contact surface with the ambientair, the natural air convection could help to dissipate the heatsignificantly. As a result, the junction working temperature of the highpower LED package 206 is reduced. Even though the liquid 204 has lowerthermal conductivity than metal or other solid material, the axialthermally conductive tube 213 and the axial fins assembly 211 havethermal conductivity so high as to fast conduct the heat from thecarrier 212 to the liquid 204 evenly, thereby enhancing the heattransformation to the liquid 204. In addition to the axial thermallyconductive tube 213 and the axial fins assembly 211 to fast conduct heatto the cooler portion of the liquid 204, this structure attainsconvection enhancement in the liquid 204. When the high power LEDpackage 206 is lighted up, the container 202 is similar to a boiler,since the high power LED package 206 in the middle of the liquid 204behaves as a heat source. In this way, the high power LED package 206warms up the neighboring portion of the liquid 204, and the warmerportion of the liquid 204 will drift upward, by which nature convectionoccurs in the liquid 204.

The container 202 may be selected according to the power consumption ofthe high power LED package 206 for smaller or larger size. Moreover, theouter surface of the container 202 is smooth, which is advantageous toairflow and thereby fast heat dissipation. The container 202 may haveits sidewall 228 reflective and its front wall 230 transparent ortranslucent. To have the reflective sidewall 228, it may be coated withmetal or optical film thereon. The container 202 is made of glass,plastic, silicone rubber or other transparent or translucent material,the carrier 212, the axial thermally conductive tube 213 and the axialfins assembly 211 are made of metal, graphite, carbon fiber, ceramic ortheir compound or other highly thermally conductive material, and theliquid 204 is preferably colorless, nonpoisonous and low viscositytransparent or translucent material, such as water, olive oil, paraffinoil and low viscosity lubricating oil. For use in the frigid zone whichhas the ambient temperature of −30° C. to 35° C., the liquid 204 iswater base added with methyl alcohol, alcohol, ethylene glycol or otherantifreeze. For use in the tropical zone which has the ambienttemperature of 35° C. to 60° C., the liquid 204 is oil based.

In some embodiments, the liquid 204 is added with tiny amount of dye,and as shown in FIG. 16, when the light 236 passes through the liquid204, the floating dye particles 238 in the liquid 204 will producereflection and refraction of the light 236, so as to enhance the sideillumination, enlarge the lighting angle, and soften the light incidentto human eyes. The dye to add in the liquid 204 may be selected fromthose colorful ones. For example, white dye is selected for white lightor colorful light applications, and other color dye is selectedconsistent with the light produced by the high power LED package 206 forspecific color applications. If the high power LED package 206 producesultraviolet light, the liquid 204 may be added with phosphorescentpowder or phosphorescent solution, by which the phosphorescent materialwill receive the ultraviolet light to release visible light. By addingvarious phosphorescent powder or phosphorescent solution in the liquid204, the lamp 200 will be a colorful fluorescent lamp. Adaptive tospecific application, the liquid 204 may be added with surfactant forthe dye or phosphorescent powder to uniform distributed in the liquid204.

The lamp 200 shown in FIG. 13 may be used as a spotlight (projectinglamp) or for ambient illumination. If the lamp 200 is a spotlight, theliquid 204 is transparent and without dye, and the container 202 hasreflective sidewall 228. There could be arranged optical lens in frontof the high power LED package 206 to guide the light emitted therefrom.If the lamp 200 is for ambient illumination, the projecting angle fromthe transparent front wall 230 is preferable greater than 110 degrees,the container 202 has transparent sidewall 228 and transparent frontwall 230, and the liquid 204 is added with tiny amount of dye.

FIG. 17 shows an embodiment of the present invention for ambientlighting, which may be used to replace the conventional bulbs. Lamp 240comprises a container 202 having a cavity 203 to fill with transparentliquid 204, light source module includes several high power LED packages206 mounted on the conical surface of highly thermally conductivecarrier 244, axial thermally conductive tube 242 fixed by positioningring 214 is mechanically connected to the carrier 244, sealing cap 216seals the aperture of the container 202, and power conversion anddriving module 220 is connected between the high power LED packages 206and standard bulb base 224 to produce DC current through the power lineswithin the axial thermally conductive tube 242 to drive the high powerLED packages 206. Axial thermally conductive rod 245 is thermallyconnected to the carrier 244 and extends along the axial direction ofthe cavity 203 for heat dissipation from the carrier 244 to the liquid204 evenly. The axial thermally conductive rod 245 has an axial lengthpreferably between ¼ and one time of the axial length of the cavity 203and thereby extends in the liquid 204 to far away from the high powerLED packages 206 such that the heat may be fast conducted from thecarrier 244 to the liquid 204. The axial thermally conductive tube 242and the axial thermally conductive rod 245 are preferably heat pipes andmade of metal, graphite, carbon fiber, ceramic or their compound. Theaxial thermally conductive rod 245 may have pillar shape or any othershape instead. In this embodiment, the container 202 has a transparentglobe, and the liquid 204 includes tiny amount of dye. In otherembodiments, the high power LED packages 206 may include various lightcolors, and could be lighted up all or part thereof at a time.

FIG. 18 shows another embodiment of the present invention for ambientlighting, which may be used to replace the conventional fluorescentlamps. In lamp 246, container includes a tube 250, light source moduleincludes two face-to-face reflective cups 252 and 253 capping at twoopposite sides of the tube 250, and two high power LED packages 206 and207 within the reflective cups 252 and 253, respectively, transparentliquid 204 with tiny amount of dye fills in the cavity 203 of thecontainer, and power supply devices 248 is electrically connected to thehigh power LED packages 206 and 207. The reflective cups 252 and 253have light focusing effect, and the tube 250 is transparent for thelight produced by the high power LED packages 206 and 207 to penetratethrough. Since the high power LED packages 206 and 207 are arranged attwo ends of the tube 250, some light will totally reflected by the tube250 and reflected and refracted by the floating dye particles in theliquid 204, thereby producing uniform lighting effect from the tube 250.In this embodiment, the reflective cups 252 and 253 are made of goodthermally conductive material to enhance the heat dissipation of thehigh power LED packages 206 and 207. However, the heat produced by thehigh power LED packages 206 and 207 is mainly transferred by the axialthermally conductive rods 251 to the liquid 204 evenly. The axialthermally conductive rod 251 immersed in the liquid 204 has a baseconnected to the carrier of either of the high power LED packages 206and 207 and extends to far away from the high power LED packages 206 and207 for stronger heat dissipation. The high power LED packages 206 and207 may be lighted up either one or both.

FIG. 19 shows an embodiment of the present invention for ultra highpower ambient lighting application. In lamp 254, light source moduleincludes a few of high power LED packages 206 each mounted on a carrier264, heat sink 256 is attached to the carriers 264 and has fins 262,several optical lens 258 are arranged in front of the high power LEDpackages 206 to produce desired lighting angle, and container 260bounded to the heat sink 256 has cavity 203 to fill with transparentliquid 204. Particularly, several axial thermally conductive rods 266are connected to the carriers 264 or the heat sink 256 for heatdissipation enhancement for the high power LED packages 206. In thisembodiment, the liquid 204 in the cavity 203 is not added with dye forwider lighting angle.

FIG. 20 shows another embodiment of the present invention for ultra highpower ambient lighting. In bulb consistent lamp 268, light source moduleincludes carrier 270 having a ring surface to mounted with a few of highpower LED packages 206 thereon, and container 274 is filled with liquid276 and bounded to the carrier 270. Other than that in the aboveembodiments, axial thermally conductive rod 272 has a base nearby butnot directly connected to the carrier 270 and a tail extending in theliquid 276 to far away from the high power LED packages 206. During thehigh power LED packages 206 work, the liquid 276 nearby the high powerLED packages 206 and the carrier 270 becomes hot, and the hightemperature liquid 276 heats up the axial thermally conductive rod 272.Therefore, the axial thermally conductive rod 272 conducts the heat fromthe light source module through the liquid 276 to the container 274evenly.

FIG. 21 shows a further enhancement of heat dissipation according to thepresent invention, which is attained by sleeving a sleeve 278 on theaxial thermally conductive rod 245 of the lamp 240 shown in FIG. 17. Asindicated by the arrows in FIG. 21, the axial thermally conductive rod245 transfers the heat from the carrier 244 to the liquid 204therearound, and the warmer liquid 204 within the sleeve 278 will driftupward, thereby causing stronger thermal convection in the liquid 204 tofurther enhance the heat dissipation.

FIG. 22 shows another bulb consistent lamp 280, in which light sourcemodule includes carrier 282 having a disc surface to mount a few of highpower LED packages 206, cap 284 covers over the high power LED packages206 such that the high power LED packages 206 and the carrier 282 arenot directly contacted by the liquid 276, container 274 is bounded tothe carrier 270 and has a cavity filled with the liquid 276, and axialthermally conductive rod 286 is thermally connected to the carrier 270to conduct the heat from the carrier 270 through the liquid 276 to thecontainer 274 evenly. The axial thermally conductive rod 286 extends inthe liquid 276 to far away from the high power LED packages 206 and thecarrier 282.

According to the present invention, it is the axial thermal conductorimmersed in the liquid for primarily dissipating the heat from theworking LED package through the liquid to the container evenly. Theaxial thermal conductor in the lamp of the present invention maycomprise heat pipe, may have tube, rod, pillar or fins shape, and may beflexible or rigid. The axial thermal conductor may or may not bedirectly connected to the carrier. If the high power LED package and thecarrier do not directly contact the liquid, the axial thermal conductoris preferably thermally connected to the carrier for good receiving theheat from the carrier. If the high power LED package and/or the carrierdirectly contact the liquid, the axial thermal conductor may only have afirst portion immersed in the liquid nearby the carrier for goodreceiving the heat from the carrier and the high power LED packagethrough the hot liquid therearound, and a second portion extending inthe liquid to far away from the carrier and the high power LED package.

According to the present invention, adaptive to applications orrequirements for high power LED in various illumination purposes, thematerial of liquid is easily to change and the geometric structure, suchas size and shape, of the container can be changed for fast heatdissipation and optimized illumination optics.

While the present invention has been described in conjunction withpreferred embodiments thereof, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and scopethereof as set forth in the appended claims.

1. An LED lamp, comprising: a tubular container having a cavity; aliquid in the cavity; two substantially face-to-face reflective cupsrespectively disposed at opposing ends of the tubular container; twolight source modules respectively mounted to the reflective cups; twoLED light sources respectively disposed within the two light sourcemodules and configured to provide light to the liquid via a front sideof the respective light source modules; and a thermal conductor having afirst portion disposed adjacent at least one of the reflective cups, anda second portion extending in a substantially axial direction of thetubular container.
 2. The lamp of claim 1, wherein at least a portion ofthe thermal conductor has a rod, tube, pillar, or fin shape.
 3. The lampof claim 1, wherein the thermal conductor comprises a heat pipe.
 4. Thelamp of claim 1, further comprising a thermally conductive carrierinterposed between one of the light source modules and the reflectivecup adjacent to the one of the light source modules.
 5. The lamp ofclaim 4, wherein the thermal conductor thermally connects to thethermally conductive carrier.
 6. The lamp of claim 1, further comprisinga sleeve on the thermal conductor.
 7. The lamp of claim 1, wherein atleast a portion of the second portion of the thermal conductor isimmersed in the liquid.
 8. The lamp of claim 1, wherein the liquidcomprises dye.
 9. The lamp of claim 1, wherein one of the reflectivecups is capable of focusing light.